1. Field of the Invention
This invention relates to acryl functional silicone compounds and to a method of preparing them.
2. Background Information
Silicone compounds which contain an acryl function are known in the art. These compounds can be acrylate, methacrylate, acrylamide, and methacrylamide. When the silicone compounds are polymeric, the known methods of preparation produce product which contains catalyst residue and other by-products of the reaction. These residues and by-products can be undesirable, especially for certain applications. One approach to overcome this problem is to remove these unwanted materials, however removal of these materials can be very difficult and expensive. Therefore a method of preparing an acryl functional silicone compound which did not produce catalyst residue or other-by-products would be a very desirable method and the resultant acryl functional silicone compounds would be purer than previously achieved directly from a process of preparation.
One method of preparing the acryl functional silicone compounds is to react a hydroxyalkylacrylate with a chlorosilicon to produce the acryl functional silicone compound with HCl as a by-product. The reaction can be run in the presence of an acid acceptor, such as an amine which makes an amine hydrochloride salt, or it can be run under partial vacuum to remove the HCl by-product, as it is formed. The amine hydrochloride salt is very difficult to remove and thus cost is high. The use of a partial vacuum to remove the gaseous HCl is also expensive. A method of making acryl functional silicone polymers by using an amine acid acceptor is described by Eckberg in U.S. Pat. No. 4,348,454, issued Sept. 7, 1982. Cully et al. in U.S. Pat. No. 4,201,808, issued May 6, 1980 describes a method of using partial vacuum to remove the HCl for the reaction of a hydroxyalkylacrylate with a chlorosilicon to produce an acryl functional silicone polymer.
Sato et al. in U.S. Pat. No. 4,293,397, issued Oct. 6, 1981, teach that an acryl functional silicone polymer can be made by reacting an amino-terminated diorganopolysiloxane with glycidyl acrylate or glycidyl methacrylate in an inert atmosphere, such as nitrogen, at temperatures of 50.degree. to 70.degree. C. for 6 to 96 hours having a polymerization inhibitor present, such as hydroquinone monomethyl ether, to prevent thermal polymerization of the acrylic acid derivative. The reaction product is a siloxane with groups of the following formula ##STR1## in which R* is hydrogen or an alkyl group of one to four carbon atoms. In view of this Sato et al. patent, the present invention was unexpected, because the acryl functional compounds of the Sato et al. patent which react with the amino-functional silicone polymer, react through the glycidyl functional group and the acryl group remains unreacted. In view of the other art and Sato et al., the reaction between the acryl functional compounds and the amino functional silicon compound would not be expected to go without a catalyst or the reaction would require conditions which would be too harsh for the acryl functional group to survive.